The invention relates to an x-ray diagnostic generator comprising an x-ray tube, a high voltage transformer supplying the x-ray tube, an inverter connected to the input of the high voltage transformer, a mains rectifier feeding the inverter and an adjustment member for the x-ray tube voltage.
An x-ray diagnostic generator of this type is described in the German Offenlegungsschrift No. 2,128,248. In the case of an x-ray diagnostic generator of this type, it is possible to select the supply frequency of the transformer in the kHz-range; i.e., substantially higher than the mains frequency. On account of this high supply frequency, the high voltage transformer can be provided with a substantially smaller and more lightweight construction than in the case of an x-ray diagnostic generator which is operated with the mains frequency. In order to regulate the x-ray tube voltage, the inverter is utilized here as a control unit. The x-ray tube voltage is controlled by determining the pulse duty factor of the output voltage of the high voltage transformer, and hence also of the inverter, in dependence upon the difference between the actual and the desired value of the x-ray tube voltage. An inverter wherein this pulse duty factor is controllable by means of a voltage corresponding to this difference is, however, very complicated in its construction.